Water pollution

Raw sewage and industrial waste in the New River as it passes from Mexicali (Mexico) to Calexico, California
Poster to teach people in South Asia about human activities leading to the pollution of water sources
Bauxite residue is an industrial waste that is dangerously alkaline and can lead to water pollution if not managed appropriately (photo from Stade, Germany).
Muddy river polluted by sediment.
Solid waste and plastics in the Lachine Canal, Canada.
The Brayton Point Power Station in Massachusetts discharges heated water to Mount Hope Bay.
A polluted river draining an abandoned copper mine on Anglesey
Perfluorooctanesulfonic acid (PFOS) is a global pollutant that has been found in drinking water. It appears not to biodegrade.
Environmental scientists preparing water autosamplers.
Oxygen depletion, resulting from nitrogen pollution and eutrophication is a common cause of fish kills.
Fecal sludge collected from pit latrines is dumped into a river at the Korogocho slum in Nairobi, Kenya.
View of secondary treatment reactors (activated sludge process) at the Blue Plains Advanced Wastewater Treatment Plant, Washington, D.C., United States. Seen in the distance are the sludge digester building and thermal hydrolysis reactors.
Silt fence installed on a construction site.
Share of water bodies with good water quality in 2020 (a water body is classified as "good" quality if at least 80% of monitoring values meet target quality levels, see also SDG 6, Indicator 6.3.2)

Contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses.

- Water pollution
Raw sewage and industrial waste in the New River as it passes from Mexicali (Mexico) to Calexico, California

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Groundwater pollution example in Lusaka, Zambia where the pit latrine in the background is polluting the shallow well in the foreground with pathogens and nitrate.

Groundwater pollution

Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way into groundwater.

Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way into groundwater.

Groundwater pollution example in Lusaka, Zambia where the pit latrine in the background is polluting the shallow well in the foreground with pathogens and nitrate.
Waterborne diseases can be spread via a groundwater well which is contaminated with fecal pathogens from pit latrines
A traditional housing compound near Herat, Afghanistan, where a shallow water supply well (foreground) is in close proximity to the pit latrine (behind the white greenhouse) leading to contamination of the groundwater.
Poor management practices in manure spreading can introduce both pathogens and nutrients (nitrate) in the groundwater system.
Schematic showing that there is a lower risk of groundwater pollution with greater depth of the water well
Sign near Mannheim, Germany indicating a zone as a dedicated "groundwater protection zone"

This type of water pollution can also occur naturally due to the presence of a minor and unwanted constituent, contaminant, or impurity in the groundwater, in which case it is more likely referred to as contamination rather than pollution.

Urban runoff entering a storm drain

Stormwater

Water that originates from precipitation , including heavy rain and meltwater from hail and snow.

Water that originates from precipitation , including heavy rain and meltwater from hail and snow.

Urban runoff entering a storm drain
Relationship between impervious surfaces and surface runoff
Stormwater carrying street bound pollutants to a storm drain for coastal discharge.
Urban runoff being discharged to coastal waters
Retention basin for management of stormwater
Volunteers clearing gutters in Ilorin, Nigeria during a volunteer sanitation day. Even when there is adequate infrastructure for sanitation, plastic pollution can interfere with storm water runoff creating space for mosquitos to breed in water, and causing flooding. Some sewage systems in the Global South are frequently overwhelmed by the waste, such as in Bangkok, Thailand.
Stormwater filtration system for urban runoff
Rain barrels can reduce runoff from building's downspouts and replace the use of potable water for activities such as gardening.
Rain garden designed to treat stormwater from adjacent parking lot
Map of municipal separate storm sewer systems
A silt fence, a type of sediment control, installed on a construction site
Public education graphic distributed by EPA

In developed environments, such as cities, unmanaged stormwater can create two major issues: one related to the volume and timing of runoff (flooding) and the other related to potential contaminants the water is carrying (water pollution).

An illustration showing groundwater in aquifers (in blue) (1, 5 and 6) below the water table (4), and three different wells (7, 8 and 9) dug to reach it.

Groundwater

Water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations.

Water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations.

An illustration showing groundwater in aquifers (in blue) (1, 5 and 6) below the water table (4), and three different wells (7, 8 and 9) dug to reach it.
Dzherelo, a common source of drinking water in a Ukrainian village
The entire surface water flow of the Alapaha River near Jennings, Florida, going into a sinkhole leading to the Floridan Aquifer groundwater
Groundwater may be extracted through a water well
Diagram of a water balance of the aquifer
Iron (III) oxide staining (after water capillary rise in a wall) caused by oxidation of dissolved iron (II) and its subsequent precipitation, from an unconfined aquifer in karst topography. Perth, Western Australia.
Groundwater withdrawal rates from the Ogallala Aquifer in the Central United States
Center-pivot irrigated fields in Kansas covering hundreds of square miles watered by the Ogallala Aquifer

Groundwater is often cheaper, more convenient and less vulnerable to pollution than surface water.

Activated sludge sewage treatment plant in Massachusetts, US

Sewage treatment

Activated sludge sewage treatment plant in Massachusetts, US
Constructed wetland (vertical flow) at Center for Research and Training in Sanitation, Belo Horizonte, Brazil
Trickling filter sewage treatment plant at Onça Treatment Plant, Belo Horizonte, Brazil.
Aeration tank of activated sludge sewage treatment plant (fine-bubble diffusers) near Adelaide, Australia
Upflow anaerobic sludge blanket (UASB) reactor in Brazil (picture from a small-sized treatment plant), Center for Research and Training in Sanitation, Belo Horizonte, Brazil
A poorly maintained anaerobic treatment pond in Kariba, Zimbabwe (sludge needs to be removed)
Preliminary treatment arrangement at small and medium-sized sewage treatment plants: Manually-cleaned screens and grit chamber (Jales Treatment Plant, São Paulo, Brazil)
Preliminary treatment: Horizontal flow grit chambers at a sewage treatment plant in Juiz de Fora, Minas Gerais, Brazil
Rectangular primary settling tanks at a sewage treatment plant in Oregon, USA
Simplified process flow diagram for a typical large-scale treatment plant using the activated sludge process.
Overall setup for a micro filtration system
Nitrification process tank at an activated sludge plant in the United States.
Constructed wetlands (vertical flow) for sewage treatment near Shanghai, China.
View of a belt filter press at the Blue Plains Advanced Wastewater Treatment Plant, Washington, D.C.
Mechanical dewatering of sewage sludge with a centrifuge at a large sewage treatment plant (Arrudas Treatment Plant, Belo Horizonte, Brazil)
Treated effluent from sewage treatment plant in Děčín, Czech Republic is discharged to surface waters.
Sludge drying beds for sewage sludge treatment at a small treatment plant at the Center for Research and Training in Sanitation, Belo Horizonte, Brazil.
Circular secondary sedimentation tank at activated sludge sewage treatment plant at Arrudas Treatment Plant, Belo Horizonte, Brazil.
Share of domestic wastewater that is safely treated (in 2018)

Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding environment or an intended reuse application, thereby preventing water pollution from raw sewage discharges.

Raw sewage arriving at a sewage treatment plant in Syria (note that protective gloves should be worn when sampling sewage).

Sewage

Type of wastewater that is produced by a community of people.

Type of wastewater that is produced by a community of people.

Raw sewage arriving at a sewage treatment plant in Syria (note that protective gloves should be worn when sampling sewage).
Pumping station lifting sewage to the treatment plant in Bujumbura, Burundi
Greywater (a component of sewage) in a settling tank
Screening of the sewage with bar screens at a sewage treatment plant to remove larger objects in Norton, Zimbabwe
Screening of sewage at a sewage treatment plant in Bujumbura, Burundi
Lack of maintenance is causing sewage to overflow from a manhole into the street of an informal settlement near Cape Town, South Africa.
Ocean outfall pipes in Cape May, New Jersey, United States – pipes exposed after the sand was removed by severe storm

All disposal options may run risks of causing water pollution.

An estuary mouth and marine coastal waters, part of an aquatic ecosystem

Aquatic ecosystem

Ecosystem in and surrounding a body of water, in contrast to land-based terrestrial ecosystems.

Ecosystem in and surrounding a body of water, in contrast to land-based terrestrial ecosystems.

An estuary mouth and marine coastal waters, part of an aquatic ecosystem

The environmental history of the Great Lakes of North America illustrates this problem, particularly how multiple stresses, such as water pollution, over-harvesting and invasive species can combine.

Storm drain with its pipe visible beneath it due to construction work

Storm drain

Infrastructure designed to drain excess rain and ground water from impervious surfaces such as paved streets, car parks, parking lots, footpaths, sidewalks, and roofs.

Infrastructure designed to drain excess rain and ground water from impervious surfaces such as paved streets, car parks, parking lots, footpaths, sidewalks, and roofs.

Storm drain with its pipe visible beneath it due to construction work
American-style curbside storm drain receiving urban runoff
Full view of a storm drain (Ontario, Canada)
Storm drain in Küstrin (now Kostrzyn nad Odrą in Poland)
A storm drain culvert under the main road empties into a bigger open channel
A truck for cleaning storm drains
The drain cover, located in Tallinn, Estonia, with a mention of sewers proximity to the sea.
Lack of proper storm drains and sewer systems in Kalibari community in Mymensingh, Bangladesh – a common situation in urban slums in developing countries
Volunteers clearing gutters in Ilorin, Nigeria during a volunteer sanitation day. Even when there is adequate infrastructure for sanitation, plastic pollution can interfere with stormwater runoff creating space for mosquitos to breed in water, and causing flooding. Some sewage systems in the Global South are frequently overwhelmed by the waste, such as in Bangkok, Thailand.
Sign alerting public to avoid dumping waste into storm drains
Typical signage embedded in pavement next to a storm drain in Boston, in the United States
Ancient Roman gully hole in Ostia Antica in Italy
A storm drain discharging into the River Brent in the UK.
Iron Cove Creek, Sydney, Australia.
Inside a large reinforced concrete box storm drain in Mississauga, Ontario, Canada.
Storm drain in Obertraun, Austria.
Storm drain overflowing in Durham, North Carolina.
114" pipe installation; Pipe: 114" aluminized type 2; Flow: 25 cubic meters/second; This is a storm drain in Guasave, Mexico.
The inlet to a storm drain in Markeaton, Derby allowing a river to overflow into the storm drain.
Inside the Markeaton Interceptor Storm Relief Culvert
Old storm drain in Kutná Hora, the Czech Republic

The performance of catch basins at removing sediment and other pollutants depends on the design of the catchbasin (for example, the size of the sump), and on routine maintenance to retain the storage available in the sump to capture sediment.

Visualisation of the distribution (by volume) of water on Earth. Each tiny cube (such as the one representing biological water) corresponds to approximately 1400 cubic km of water, with a mass of approximately 1.4 trillion tonnes (235000 times that of the Great Pyramid of Giza or 8 times that of Lake Kariba, arguably the heaviest man-made object). The entire block comprises 1 million tiny cubes.

Fresh water

Any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids.

Any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids.

Visualisation of the distribution (by volume) of water on Earth. Each tiny cube (such as the one representing biological water) corresponds to approximately 1400 cubic km of water, with a mass of approximately 1.4 trillion tonnes (235000 times that of the Great Pyramid of Giza or 8 times that of Lake Kariba, arguably the heaviest man-made object). The entire block comprises 1 million tiny cubes.
A graphical distribution of the locations of water on Earth. Only 3% of the Earth's water is fresh water. Most of it is in icecaps and glaciers (69%) and groundwater (30%), while all lakes, rivers and swamps combined only account for a small fraction (0.3%) of the Earth's total freshwater reserves.

Fresh water can easily become polluted by human activities or due to naturally occurring processes, such as erosion.

Muddy river

Nonpoint source pollution

Nonpoint source (NPS) pollution refers to diffuse contamination (or pollution) of water or air that does not originate from a single discrete source.

Nonpoint source (NPS) pollution refers to diffuse contamination (or pollution) of water or air that does not originate from a single discrete source.

Muddy river
Runoff of soil and fertilizer during a rain storm
Nonpoint source pollution is caused when precipitation (1) carries pollutants from the ground such as nitrogen (N) and phosphorus (P) pollutants which come from fertilizers used on farm lands (2) or urban areas (3). These nutrients can cause eutrophication (4).
Contour buffer strips used to retain soil and reduce erosion

Nonpoint source water pollution affects a water body from sources such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea.

Waterborne diseases can be spread via groundwater which is contaminated with fecal pathogens from pit latrines.

Waterborne diseases

Waterborne diseases are conditions (meaning adverse effects on human health, such as death, disability, illness or disorders) caused by pathogenic micro-organisms that are transmitted in water.

Waterborne diseases are conditions (meaning adverse effects on human health, such as death, disability, illness or disorders) caused by pathogenic micro-organisms that are transmitted in water.

Waterborne diseases can be spread via groundwater which is contaminated with fecal pathogens from pit latrines.
Hepatitis A virusHepatitis A is one of waterborne diseases and its symptoms are only acute. Symptoms include fatigue, fever, etc.

The term waterborne disease is reserved largely for infections that predominantly are transmitted through contact with or consumption of microbially polluted water.